Okay kiddo, imagine you're looking at a map of the moon. Just like on a map of Earth, you can use lines and grids to help you figure out where things are. Scientists have created a special set of lines and grids just for the moon, called the selenographic coordinate system.
The selenographic coordinate system is a way of using numbers and letters to talk about different locations on the moon. It's like a secret code that scientists use to describe where things are.
The lines are vertical and horizontal, just like the lines on graph paper. The horizontal lines are called parallels and the vertical lines are called meridians. On Earth, these lines are based on the equator and the prime meridian, but on the moon, they're based on different things.
There are two main points that the selenographic coordinate system is based on. One is a point called the lunar north pole, which is the point on the moon's surface that is closest to the moon's north pole. The other is a point called the lunar prime meridian, which is basically like the moon's version of the longitude line.
To describe a location on the moon using the selenographic coordinate system, scientists use two numbers and a letter. The first number is the latitude, which tells you how far north or south of 0° (the lunar equator) the location is. The second number is the longitude, which tells you how far east or west of the lunar prime meridian the location is. The letter is either N, S, E, or W, and tells you whether the location is north, south, east, or west of the lunar prime meridian.
So there you have it, the selenographic coordinate system is a way for scientists to talk about different parts of the moon using a special code of numbers and letters based on the lunar north pole and lunar prime meridian.